drivers/of/base.c

   1 /*
   2  * Procedures for creating, accessing and interpreting the device tree.
   3  *
   4  * Paul Mackerras       August 1996.
   5  * Copyright (C) 1996-2005 Paul Mackerras.
   6  *
   7  *  Adapted for 64bit PowerPC by Dave Engebretsen and Peter Bergner.
   8  *    {engebret|bergner}@us.ibm.com
   9  *
  10  *  Adapted for sparc and sparc64 by David S. Miller davem@davemloft.net
  11  *
  12  *  Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell.
  13  *
  14  *      This program is free software; you can redistribute it and/or
  15  *      modify it under the terms of the GNU General Public License
  16  *      as published by the Free Software Foundation; either version
  17  *      2 of the License, or (at your option) any later version.
  18  */
  19 #include <linux/module.h>
  20 #include <linux/of.h>
  21 #include <linux/spinlock.h>
  22
  23 struct device_node *allnodes;
  24
  25 /* use when traversing tree through the allnext, child, sibling,
  26  * or parent members of struct device_node.
  27  */
  28 DEFINE_RWLOCK(devtree_lock);
  29
  30 int of_n_addr_cells(struct device_node *np)
  31 {
  32         const int *ip;
  33
  34         do {
  35                 if (np->parent)
  36                         np = np->parent;
  37                 ip = of_get_property(np, "#address-cells", NULL);
  38                 if (ip)
  39                         return *ip;
  40         } while (np->parent);
  41         /* No #address-cells property for the root node */
  42         return OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
  43 }
  44 EXPORT_SYMBOL(of_n_addr_cells);
  45
  46 int of_n_size_cells(struct device_node *np)
  47 {
  48         const int *ip;
  49
  50         do {
  51                 if (np->parent)
  52                         np = np->parent;
  53                 ip = of_get_property(np, "#size-cells", NULL);
  54                 if (ip)
  55                         return *ip;
  56         } while (np->parent);
  57         /* No #size-cells property for the root node */
  58         return OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
  59 }
  60 EXPORT_SYMBOL(of_n_size_cells);
  61
  62 struct property *of_find_property(const struct device_node *np,
  63                                   const char *name,
  64                                   int *lenp)
  65 {
  66         struct property *pp;
  67
  68         read_lock(&devtree_lock);
  69         for (pp = np->properties; pp != 0; pp = pp->next) {
  70                 if (of_prop_cmp(pp->name, name) == 0) {
  71                         if (lenp != 0)
  72                                 *lenp = pp->length;
  73                         break;
  74                 }
  75         }
  76         read_unlock(&devtree_lock);
  77
  78         return pp;
  79 }
  80 EXPORT_SYMBOL(of_find_property);
  81
  82 /*
  83  * Find a property with a given name for a given node
  84  * and return the value.
  85  */
  86 const void *of_get_property(const struct device_node *np, const char *name,
  87                          int *lenp)
  88 {
  89         struct property *pp = of_find_property(np, name, lenp);
  90
  91         return pp ? pp->value : NULL;
  92 }
  93 EXPORT_SYMBOL(of_get_property);
  94
  95 /** Checks if the given "compat" string matches one of the strings in
  96  * the device's "compatible" property
  97  */
  98 int of_device_is_compatible(const struct device_node *device,
  99                 const char *compat)
 100 {
 101         const char* cp;
 102         int cplen, l;
 103
 104         cp = of_get_property(device, "compatible", &cplen);
 105         if (cp == NULL)
 106                 return 0;
 107         while (cplen > 0) {
 108                 if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
 109                         return 1;
 110                 l = strlen(cp) + 1;
 111                 cp += l;
 112                 cplen -= l;
 113         }
 114
 115         return 0;
 116 }
 117 EXPORT_SYMBOL(of_device_is_compatible);
 118
 119 /**
 120  *  of_device_is_available - check if a device is available for use
 121  *
 122  *  @device: Node to check for availability
 123  *
 124  *  Returns 1 if the status property is absent or set to "okay" or "ok",
 125  *  0 otherwise
 126  */
 127 int of_device_is_available(const struct device_node *device)
 128 {
 129         const char *status;
 130         int statlen;
 131
 132         status = of_get_property(device, "status", &statlen);
 133         if (status == NULL)
 134                 return 1;
 135
 136         if (statlen > 0) {
 137                 if (!strcmp(status, "okay") || !strcmp(status, "ok"))
 138                         return 1;
 139         }
 140
 141         return 0;
 142 }
 143 EXPORT_SYMBOL(of_device_is_available);
 144
 145 /**
 146  *      of_get_parent - Get a node's parent if any
 147  *      @node:  Node to get parent
 148  *
 149  *      Returns a node pointer with refcount incremented, use
 150  *      of_node_put() on it when done.
 151  */
 152 struct device_node *of_get_parent(const struct device_node *node)
 153 {
 154         struct device_node *np;
 155
 156         if (!node)
 157                 return NULL;
 158
 159         read_lock(&devtree_lock);
 160         np = of_node_get(node->parent);
 161         read_unlock(&devtree_lock);
 162         return np;
 163 }
 164 EXPORT_SYMBOL(of_get_parent);
 165
 166 /**
 167  *      of_get_next_parent - Iterate to a node's parent
 168  *      @node:  Node to get parent of
 169  *
 170  *      This is like of_get_parent() except that it drops the
 171  *      refcount on the passed node, making it suitable for iterating
 172  *      through a node's parents.
 173  *
 174  *      Returns a node pointer with refcount incremented, use
 175  *      of_node_put() on it when done.
 176  */
 177 struct device_node *of_get_next_parent(struct device_node *node)
 178 {
 179         struct device_node *parent;
 180
 181         if (!node)
 182                 return NULL;
 183
 184         read_lock(&devtree_lock);
 185         parent = of_node_get(node->parent);
 186         of_node_put(node);
 187         read_unlock(&devtree_lock);
 188         return parent;
 189 }
 190
 191 /**
 192  *      of_get_next_child - Iterate a node childs
 193  *      @node:  parent node
 194  *      @prev:  previous child of the parent node, or NULL to get first
 195  *
 196  *      Returns a node pointer with refcount incremented, use
 197  *      of_node_put() on it when done.
 198  */
 199 struct device_node *of_get_next_child(const struct device_node *node,
 200         struct device_node *prev)
 201 {
 202         struct device_node *next;
 203
 204         read_lock(&devtree_lock);
 205         next = prev ? prev->sibling : node->child;
 206         for (; next; next = next->sibling)
 207                 if (of_node_get(next))
 208                         break;
 209         of_node_put(prev);
 210         read_unlock(&devtree_lock);
 211         return next;
 212 }
 213 EXPORT_SYMBOL(of_get_next_child);
 214
 215 /**
 216  *      of_find_node_by_path - Find a node matching a full OF path
 217  *      @path:  The full path to match
 218  *
 219  *      Returns a node pointer with refcount incremented, use
 220  *      of_node_put() on it when done.
 221  */
 222 struct device_node *of_find_node_by_path(const char *path)
 223 {
 224         struct device_node *np = allnodes;
 225
 226         read_lock(&devtree_lock);
 227         for (; np; np = np->allnext) {
 228                 if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
 229                     && of_node_get(np))
 230                         break;
 231         }
 232         read_unlock(&devtree_lock);
 233         return np;
 234 }
 235 EXPORT_SYMBOL(of_find_node_by_path);
 236
 237 /**
 238  *      of_find_node_by_name - Find a node by its "name" property
 239  *      @from:  The node to start searching from or NULL, the node
 240  *              you pass will not be searched, only the next one
 241  *              will; typically, you pass what the previous call
 242  *              returned. of_node_put() will be called on it
 243  *      @name:  The name string to match against
 244  *
 245  *      Returns a node pointer with refcount incremented, use
 246  *      of_node_put() on it when done.
 247  */
 248 struct device_node *of_find_node_by_name(struct device_node *from,
 249         const char *name)
 250 {
 251         struct device_node *np;
 252
 253         read_lock(&devtree_lock);
 254         np = from ? from->allnext : allnodes;
 255         for (; np; np = np->allnext)
 256                 if (np->name && (of_node_cmp(np->name, name) == 0)
 257                     && of_node_get(np))
 258                         break;
 259         of_node_put(from);
 260         read_unlock(&devtree_lock);
 261         return np;
 262 }
 263 EXPORT_SYMBOL(of_find_node_by_name);
 264
 265 /**
 266  *      of_find_node_by_type - Find a node by its "device_type" property
 267  *      @from:  The node to start searching from, or NULL to start searching
 268  *              the entire device tree. The node you pass will not be
 269  *              searched, only the next one will; typically, you pass
 270  *              what the previous call returned. of_node_put() will be
 271  *              called on from for you.
 272  *      @type:  The type string to match against
 273  *
 274  *      Returns a node pointer with refcount incremented, use
 275  *      of_node_put() on it when done.
 276  */
 277 struct device_node *of_find_node_by_type(struct device_node *from,
 278         const char *type)
 279 {
 280         struct device_node *np;
 281
 282         read_lock(&devtree_lock);
 283         np = from ? from->allnext : allnodes;
 284         for (; np; np = np->allnext)
 285                 if (np->type && (of_node_cmp(np->type, type) == 0)
 286                     && of_node_get(np))
 287                         break;
 288         of_node_put(from);
 289         read_unlock(&devtree_lock);
 290         return np;
 291 }
 292 EXPORT_SYMBOL(of_find_node_by_type);
 293
 294 /**
 295  *      of_find_compatible_node - Find a node based on type and one of the
 296  *                                tokens in its "compatible" property
 297  *      @from:          The node to start searching from or NULL, the node
 298  *                      you pass will not be searched, only the next one
 299  *                      will; typically, you pass what the previous call
 300  *                      returned. of_node_put() will be called on it
 301  *      @type:          The type string to match "device_type" or NULL to ignore
 302  *      @compatible:    The string to match to one of the tokens in the device
 303  *                      "compatible" list.
 304  *
 305  *      Returns a node pointer with refcount incremented, use
 306  *      of_node_put() on it when done.
 307  */
 308 struct device_node *of_find_compatible_node(struct device_node *from,
 309         const char *type, const char *compatible)
 310 {
 311         struct device_node *np;
 312
 313         read_lock(&devtree_lock);
 314         np = from ? from->allnext : allnodes;
 315         for (; np; np = np->allnext) {
 316                 if (type
 317                     && !(np->type && (of_node_cmp(np->type, type) == 0)))
 318                         continue;
 319                 if (of_device_is_compatible(np, compatible) && of_node_get(np))
 320                         break;
 321         }
 322         of_node_put(from);
 323         read_unlock(&devtree_lock);
 324         return np;
 325 }
 326 EXPORT_SYMBOL(of_find_compatible_node);
 327
 328 /**
 329  * of_match_node - Tell if an device_node has a matching of_match structure
 330  *      @matches:       array of of device match structures to search in
 331  *      @node:          the of device structure to match against
 332  *
 333  *      Low level utility function used by device matching.
 334  */
 335 const struct of_device_id *of_match_node(const struct of_device_id *matches,
 336                                          const struct device_node *node)
 337 {
 338         while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
 339                 int match = 1;
 340                 if (matches->name[0])
 341                         match &= node->name
 342                                 && !strcmp(matches->name, node->name);
 343                 if (matches->type[0])
 344                         match &= node->type
 345                                 && !strcmp(matches->type, node->type);
 346                 if (matches->compatible[0])
 347                         match &= of_device_is_compatible(node,
 348                                                 matches->compatible);
 349                 if (match)
 350                         return matches;
 351                 matches++;
 352         }
 353         return NULL;
 354 }
 355 EXPORT_SYMBOL(of_match_node);
 356
 357 /**
 358  *      of_find_matching_node - Find a node based on an of_device_id match
 359  *                              table.
 360  *      @from:          The node to start searching from or NULL, the node
 361  *                      you pass will not be searched, only the next one
 362  *                      will; typically, you pass what the previous call
 363  *                      returned. of_node_put() will be called on it
 364  *      @matches:       array of of device match structures to search in
 365  *
 366  *      Returns a node pointer with refcount incremented, use
 367  *      of_node_put() on it when done.
 368  */
 369 struct device_node *of_find_matching_node(struct device_node *from,
 370                                           const struct of_device_id *matches)
 371 {
 372         struct device_node *np;
 373
 374         read_lock(&devtree_lock);
 375         np = from ? from->allnext : allnodes;
 376         for (; np; np = np->allnext) {
 377                 if (of_match_node(matches, np) && of_node_get(np))
 378                         break;
 379         }
 380         of_node_put(from);
 381         read_unlock(&devtree_lock);
 382         return np;
 383 }
 384 EXPORT_SYMBOL(of_find_matching_node);